U.S. DEPARTMENT OF THE INTERIOR 

U.S. GEOLOGICAL SURVEY

Gas:Oil Ratios for Source Rocks Containing Type-I, -II, -US, and -HI Kerogens 

as Determined by Hydrous Pyrolysis

by 

Michael D. Lewan1 and AJlison A. Henry1 *

Open File Report No. 99-327

This report is preliminary and has not been reviewed for conformity with U. S. Geo'ogical 

Survey editorial standards (or with the North American Stratigraphic Code). Any use of 

trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U. S. Government.

1 U. S. Geological Survey, Box 25046, MS 977, Denver Federal Center, 

Denver, CO 80225 (e-mail: mlewan@usgs.gov)

* Current Address: The Scripps Research Institute, 10550 North Torrey Pines Road, La 

Jolla, CA 92037 (e-mail: ahenry@scripps.edu)
INTRODUCTION

Predicting the gas:oil ratio (GOR) of a petroleum play or prospect is important in 

evaluating the economics of an exploration venture and in assessing petroleum resources. 

Estimates of the GOR of prospects in well-drilled areas can typically be determined with 

analogs from neighboring production in the same play. In poorly drilled areas, GOR of 

prospects may be estimated by using analogs from more distant well-drilled plays that have 

similar geological settings or by models based on oil and gas generation from potential 

source rocks (e.g., Mackenzie and Quigley, 1988; and Kuo and Michael, 1994). GORs 

have also been determined by hydrous pyrolysis of potential source rocks in an exploration 

play or petroleum system (e.g., Noble and others, 1991; and Lillis and others, 1999). 

Unlike open- or closed-system anhydrous pyrolysis, hydrous pyrolysis generates an 

expelled oil that is physically and chemically similar to natural crude oil (Lewan, 1993 a; 

1997). As a result, the quantity of this expelled oil and the gas generated allows one to 

calculate GORs of a particular source rock at hydrous-pyrolysis temperatures representing 

different stages of oil generation.

The objectives of this report are to present GORs from hydrous pyrolysis 

experiments conducted on immature source rocks and report how they are affected by 

kerogen type and thermal maturity during petroleum generation. The source rocks used in 

this study contain the major kerogen types, including Type-I, -II, -US, and -III. 

Thermally immature samples were used to provide a complete understanding of changes in 

GOR from incipient petroleum generation through peak petroleum generation.

METHODS

Source Rock Samples: Experimental data were available on five immature source rocks, 

which are described in Table 1. The major kerogen types in these source rocks include 

Type-I, -II, -US, and -III. Collaborators that collected and pyrolyzed aliquots of these 

samples are also referenced in Table 1. With respect to vitrinite reflectance (%Ro), all of 

these sample have initial random mean %Ro values equal to or less than 0.5 or atomic H/C 

and O/C ratios indicative of pre-catagenesis (i.e., diagenesis) according to Tissot and 

Welte (1984; Fig. II.5.1, p.161).

Hydrous Pyrolysis Experiments: Complete details of hydrous pyrolysis experiments are 

given by Lewan (1993a). Briefly, the experiments consist of isothermally heating several 

hundred grams of gravel-sized immature source rock in the presence of liquid water in 

one-liter stainless-steel reactors at subcritical-water temperatures (<374°C) for several 

days (2-10 days). After the experiment is completed and allowed to cool to room 

temperatures (20-25°C), the gas pressure and temperature are recorded and a gas sample 

is collected in 30-cm3 stainless-steel cylinders. Gas compositions were determined by 

mass spectometry according to an enhanced version of the ASTM D2650-88 method. 

The remaining gas is vented and the reactor is opened to quantitatively collect the expelled 

oil, which floats on the water surface above the submerged source rock. All of the 

experiments considered in this study were conducted for 72 hours at temperatures ranging 

from 160 to 365°C (Table 2). These experimental conditions simulate thermal maturities 

associated with oil generation. Atomic H/C and O/C ratios of kerogens at temperatures 

equal to or less than 355°C for 72 hours indicate that the samples have only been
subjected to catagenesis according to Tissot and Welte (1984, Fig. II.5.1, p. 161). Lowrank coals (< 0.5%Ro) subjected to hydrous pyrolysis at 355°C for 72 hours obtain 

random mean vitrinite reflectance values of 1.55 %Ro (Lewan, 1993b).

Gas Volume Calculations: The first step in calculating a gas volume is to determine the 

number of moles of hydrocarbon gas generated, which consists of methane, ethane, 

propane, w-butane, /-butane, /z-pentane and /-pentane. The number of moles of total gas at 

the end of each experiment, nM, was calculated by the ideal gas law :

nlot = (PV)/(RT), (1)

where P is the measured cool-down pressure, T is the measured cool-down temperature, 

V is the head-space gas volume, and R is the ideal gas constant. The number of moles of 

each of the component hydrocarbon gases is calculated using gas analyses, which are 

reported in mole percent of the total gas. The number of moles of each hydrocarbon gas 

is summed to give the number of moles of hydrocarbon gas generated in the experiment, 

HHC- Assuming that these gases behaved ideally at room temperatures, the volume of 

hydrocarbon gas at 14.7 psi and 288.71 K, VHcgas, was determined by rearranging th? ideal 

gas equation:

VHc= (n1ICRT)/P, (2)

where P is 14.7 psia, T is 288.71 K, Hue T\mt]ltw + ncu,a.ie+ rvPane+ n,,.buume + 

rUutane + IX,., ,^ + Hy-pentanc, and R is 1206.00 (cm3.psi)/(mol.K). Equation 2 gives the 

volume in cubic centimeters. This quantity is multiplied by 3.5314667 x 10"5 to grfe the 

volume of hydrocarbon gas in standard cubic feet (scf):

V«c (ft3) = V,JC (cm3) x 3.314667 x 10'5 . (3)

In this report, gas volumes are given in units of mc#kg TOC (e.g., Table 3 and Figure 1). 

For clarification, mcf is milli-standard cubic feet (i.e., scf x 10"3) and kg TOC is the mass 

of total organic carbon (TOC) in the original unheated sample.

Oil Volume Calculations: The volume of oil generated in each experiment was calculated 

by dividing the total mass of oil in grams, rrioa, by its density in grams per cubic centimeter,

doa :

You (cm3) = (mofl) / (cL). : (4)

The resulting cubic centimeters of oil is divided by 158982.84 to convert the volume of oil 

to barrels:
Voa (bbls) = VPil (cm3) / 158982.84 . (5)

Densities of all the expelled oils (cL) generated by hydrous pyrolysis were not determined, 

but typically their API gravities range between 25° and 42°, which equates to densities of 

0.904 and 0.816 g/cm3/, respectively. For this study, a density of 0.876 cm3/g (30.0° API 

gravity) was used to calculate volumes for all the oils generated by hydrous pyrolysis.

Gas to Oil Ratio (GOR) Calculations: GORs in scf/bbl were calculated by dividing the 

volume of hydrocarbon gas by the volume of oil generated in the experiment.

GOR (ft/bbl) = Vuc (ft3) / You (bbls) (6)

A sensitivity test was conducted to evaluate the effect a range of API gravities between 

25° and 42° had on calculated GORs. The average difference in GORs calculated with 

densities of 0.816 and 0.904 g/cm3 for all the experiments considered in this study is 84 ± 

57 scf/bbl. This difference in GORs indicates that the use of a constant oil density of 

0.876 g/cm3 (30.0°API gravity) has no significant effect on the calculated GORs presented 

in this study. As indicated in Table 3, GORs are only calculated for experiments in which 

an expelled oil is generated. Therefore, no GORs are calculated at temperatures below 

270°C.

RESULTS

The amount of hydrocarbon gas generated from the source rocks containing the 

different kerogen types is given in Table 3. Figure 1 shows an exponential increase in 

hydrocarbon gas generated with increasing experimental temperature for all the source 

rocks. The two source rocks containing Type-IIS kerogen generate the most 

hydrocarbon gas, which at 350°C is more than twice that generated by the T}'pe-III 

kerogen in the lignite (Table 3). Source rocks containing Type-I and -II kerogens 

generate similar amounts of hydrocarbon gases, which at 350°C are slightly less thrn that 

generated by the Type-IIS kerogens but nearly twice that generated by the Type-Ill 

kerogen in the lignite (Table 3).

The GORs for the source rocks containing the different kerogen types are given in 

Table 3. Figure 2 shows a curvilinear decrease in GOR with increasing experimental 

temperature for all the source rocks, with the exception of the slight increase at 

temperatures greater than 340°C for the Type-IIS kerogens. At 350°C for 72h, the GORs 

for the Type-IIS and -I kerogens are similar and range between 401 and 527 scf/bbl (Table 

3). Type-II and -III kerogens at these same experimental conditions have significantly 

higher GORs of 935 and 883 scf/bbl, respectively. These two kerogen types alsc have 

consistently higher GORs at the lower experimental temperatures with the except'-on of 

the Type-II kerogen at 285°C for 72h. Overall, GORs during oil generation are between 

500 and 1500 scf/bbl irrespective of kerogen type.
DISCUSSION

Amounts of Gas Generated: Type-Ill kerogen is typically described as a gas-prone 

source (Hunt, 1996, and references therein). Although Type-Ill kerogen has the highest 

GOR during catagenesis (Figure 2), it generates the lowest amounts of hydrocarbon gas 

compared with the oil-prone kerogens (i.e., Type-I, -II, and -US). Previously reported 

hydrous pyrolysis results have also shown that Type-I and -II kerogens generate 

significantly more gas than Type-Ill kerogen (Lewan, 1993c; Hunt, 1996, p. 601, Table 

16-3). These results are also in general agreement with open-system pyrolysis results as 

modeled by Behar and others (1997) and the composite- pyrolysis model by Pepper and 

Corvi (1995). An implication of these results is that oil-prone kerogens can be the source 

of more hydrocarbon gas during catagenesis than so called gas-prone Type-111 kerogen.

The only notable contradiction between the hydrous pyrolysis and the open-system 

pyrolysis by Behar and others (1997) is that the Type-IIS kerogen does not generate the 

highest amount of hydrocarbon gas in the open-system pyrolysis as observed in Ii5fdrous 

pyrolysis (Figure 1). However, the composite-pyrolysis model by Pepper and Corvi 

(1995) predicts that Type-IIS kerogen generates the most hydrocarbon gas, which is in 

agreement with the hydrous pyrolysis results. Hydrous pyrolysis experiments conducted 

by Seewald and others (1998) also showed that Type-IIS kerogen in a sample of 

Monterey Shale generated four times as much hydrocarbon gas as Type-Ill kerogen in 

samples of the Smackover and Eutaw shales. These experimental observations suggest 

that petroleum systems that produce high-sulfur oils from Type-IIS kerogen should also 

have appreciable quantities of hydrocarbon gas associated with them.

The exponential increase in hydrocarbon generation with increasing temperature 

(Figure 1) raises the questions whether this increase in gas generation continues through 

metagenesis and what is the maximum amount of gas that can be generated from a source 

rock. It should be noted that the results from the hydrous pyrolysis experiments represent 

a closed-system in which gas may be generated from the decomposition of kerogen or 

bitumen retained in a rock, as well as from the expelled oil on the water surface within the 

closed reactor. It is interesting that with all these possible sources for gas, there rre no 

obvious breaks in the slope of gas generation that would suggest changes in the source of 

gas with increasing temperature. Additional experiments are needed to determine the 

extent of this exponential increase in hydrocarbon gas and the maximum amount of 

hydrocarbon gas that can be generated from different source materials (i.e., kerogen, 

bitumen, and oil).

Clay-mineral catalysis has been suggested to play an important role in petroleum 

generation (Johns and Shimoyama, 1972; Goldstein, 1983). However, experimental 

pyrolysis results indicate that the presence of clay minerals has no significant effect on 

generation of methane and ethane from kerogen (Tannenbaum and Kaplan, 1985). 

Although results from our study are not unequivocal in indicating that clay-mineral 

catalysis is not important in gas generation, they do suggest that clay minerals in a source 

rock are not essential to hydrocarbon gas generation. Specifically, the two source rocks 

containing Type-IIS kerogen in this study are limestones and generate the most 

hydrocarbon gas despite their low clay-mineral content. In addition, the claystone with 

Type-II kerogen does not generate significantly greater amounts of hydrocarbon gar than
the marlstone with Type-I kerogen despite the higher clay-mineral content of the former 

(Table 3).

Gas:Oil Ratios (GORs): Figure 3 shows that hydrous-pyrolysis GORs during oil 

generation are between 400 and 3000 scf/bbl. These GORs are within the range of values 

(<5000 scf/bbl) prescribed by Larter and Mills (1991) for petroleum expelled from source 

rocks based on pyrolysis-gas chromatography. England and Mackenzie (1989) refer to 

these expelled GORs as "feedstock" GORs, which they suggest range between 1000-2500 

scf/bbl. Although these GOR ranges are in agreement with those derived from hydrous 

pyrolysis (Table 3 and Figure 2), there is a major difference in the way these GORs change 

with maturation during oil generation. Figure 2 shows GORs derived from hydrous 

pyrolysis decrease during oil generation. The more gas-prone Type-Ill kerogen in the 

Wilcox lignite decreases from 2831 scf/bbl at 280°C for 72h to 883 scf/bbl at 350°C for 

72h. The oil-prone Type-I, -II, and -US kerogens decrease from 2381 scf/bbl at 270°C for 

72h to 401-935 scf/bbl at 350°C for 72h: As shown in Figure 3, these decreasing 

hydrous-pyrolysis GORs are contrary to the increasing GORs derived from closed-system 

anhydrous pyrolysis as reported by Quigley and Mackenzie (1988). These authors state 

that their trend is representative of most source rocks irrespective of differences in 

lithology.

These conflicting results can be explained by differences in the products generated 

by closed-system anhydrous and hydrous pyrolysis. In hydrous pyrolysis, only the 

expelled oil and generated gas are used in the calculation of the GOR. In anhydrous 

pyrolysis, no expelled oil is generated, so GORs are calculated with the generated gas and 

solvent-soluble or thermally-labile bitumen in the.rock. In addition, Lewan (1997) shows 

that cross-linking reactions resulting in the formation of pyrobitumen (i.e., insoluble char 

or inert carbon) are more prevalent in closed-system anhydrous pyrolysis than in hydrous 

pyrolysis. Therefore, the anhydrous-pyrolysis GORs increase with temperature as soluble 

or labile bitumen decreases and generated gas increases to a greater extent than in hydrous 

pyrolysis. The contrary GOR trends determined by these two different pyrolysis methods 

are shown in Figure 4, which is based on closed-system anhydrous and hydrous pyrolysis 

experiments conducted on aliquots of the same sample of Woodford Shale (Lewan, 1997). 

An important implication of this difference is that GORs derived from hydrous pyrolysis 

indicate that source rocks in the early stages of oil generation can generate accumulations 

with GORs between 1500 and 3000 scf/bbl. Conversely, GORs derived from closedsystem anhydrous pyrolysis indicate source rocks in the early stages of oil generation can 

only generate accumulations with GORs less than 1000 scf/bbl.

Although the hydrous-pyrolysis GORs decrease during most of oil generation, it is 

expected that this GOR trend will reverse and increase after oil generation. This increase 

would not be the result of additional oil generation but of additional gas generation from 

the thermal decomposition of the remaining kerogen and bitumen within the source rock 

and the expelled oil on the water surface. Source 'rocks with Type-US kerogen show a 

distinct GOR increase at the higher temperatures (>340°C) that suggests the start of this 

anticipated increase (Figure 2). An important question that remains is whether tH gas 

generated after oil generation is from the kerogen and bitumen remaining in the source
rock or from the expelled oil? Additional hydrous-pyrolysis experiments on oil and 

mature source rock are needed to resolve this question.

CONCLUSIONS

GORs for a given source rock can be derived from hydrous pyrolysis experiments. 

During oil generation, source rocks with oil-prone kerogen (i.e., Type-I, -II, and -US) 

generate hydrous-pyrolysis GORs between 382 and 2381 scfTbbl. Source rod's with 

Type-Ill kerogen generate higher GORs (883-2831 scf/bbl) than source rocks with more 

oil-prone kerogen (i.e., Type-I, -II, and -US) during catagenesis (oil generation). 

However, the more oil-prone kerogens can generate twice as much hydrocarbon gas per 

gram of organic carbon as the more gas-prone Type-Ill kerogen .

During oil generation, GORs determined by closed-system anhydrous pyrolysis 

increase with increasing temperature, and GORs determined by hydrous pyrolysis initially 

decrease with increasing temperature. As a result, hydrous-pyrolysis GORs indicate that 

petroleum accumulations with GORs between 1500 and 3000 scf/bbl can be generated 

during the early stages of oil generation. Conversely, anhydrous-pyrolysis GORs indicate 

that petroleum accumulations with GORs greater than 2000 scfTbbl can only be generated 

near the end of oil generation.

In conjunction with the recommendations made by Henry and Lewan (1999), more 

hydrous-pyrolysis experimental work is needed to quantitatively understand the controls 

on gas generation from source rocks and expelled oil. These experiments should be 

designed to determine if the exponential increase in hydrocarbon-gas generation and an 

increase in GORs occurs past oil generation and into metaganesis. Experiments should 

also be designed to evaluate whether this late-stage hydrocarbon gas is generated from 

organic components retained in the source rock or from expelled oil.

ACKNOWLEDGEMENTS

This study was funded in part by the U. S. Department of Energy (Federal Energy 

Technology Center, Morgantown, WV, contract no. DE-AT26-98FT40032), Gas 

Research Institute (Chicago, IL) as a Cooperative Research and Development Agreement 

with Advanced Resources International (Arlington, VA), and the Central Energy Team of 

the U. S. Geological Survey (Denver, CO). The authors also appreciate the helpful 

reviews of this report made by Paul Lillis, Thaddeus Dyman, and Katharine Tfarnes 

(USGS). The authors also acknowledge the collaborative experimental work of Tim 

Ruble (CSIRO, Australia), J. Guthrie (Mobil, Dallas), Eli Tannenbaum (Kimron, Israel), 

Hasim Ramini (NRA, Jordan), Francoise Behar (IFF, France), Francois Lorant (IFF, 

France), and Robert Dias (Penn State University), which provided the basic gas data used 

in this report.
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cracking of kerogen in open and closed systems: determination of kinetic 

parameters and stoichiometric coefficients for oil and gas generation: Org. 

Geochem. 26, p. 321-339.

Dias, R. F., Freeman, K. H., Lewan, M. D., and Franks, S. G., 1997, Kerogen maturation 

and the 6 13C of organic acids in oil-associated waters: American Association cf 

Petroleum Geologists Annual Meeting, Dallas, TX, April 6-9, 1997, Program and 

Abstracts, v. 6, pp. A27-A28.

England, W. A. and Mackenzie, A. S., 1989, Some aspects of the organic geochemistry of 

petroleum fluids: Geologische Rundschau 78, p. 291-303.

Goldstein, T. P., 1983, Geocatalytic reactions in formation and maturation of petroleum: 

American Association of Petroleum Geologists Bulletin 67, pp. 152-159.

Henry, A. A. and Lewan, M. D., 1999, Comparison of kinetic-model predictions of 

deep-gas generation: U. S. Geological Survey, Open File Report 99-in review.

Hunt, J. M., 1996, Petroleum Geochemistry and Geology: W. H. Freeman and Company, 

New York, 743 p.

Johns, W. D. and Shimoyama, A., 1972, Clay minerals and petroleum-forming react: ons 

during burial and diagenesis: American Association of Petroleum Geologists 

Bulletin^, p. 2160-2167.

Kuo, L.-C., and Michael, G. E., 1994, A multicomponent oil-cracking kinetics mode1 for 

modeling preservation and composition of reservoired oils: Org. Geochem. 11, 

p. 911-925.

Larter, S. and Mills, N., 1991, Phase-controlled molecular fractionations in migrating 

petroleum charges: in England, W. A. and Fleet, A. J. (eds.j, Petroleum 

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in Engel, M., and Macko, S., eds., Organic Geochemistry, Plenum Publications 

Corp., New York, p. 419-442.

Lewan, M.D., 1993b, Identifying and understanding suppressed vitrinite reflectance

through hydrous pyrolysis experiments: Society for Organic Petrology, Abstracts 

and Program, v. 10, p. 1-3.
Lewan, M.D., 1993c, Hydrocarbon gas generation from different kerogen types subjected 

to hydrous pyrolysis: American Chemical Society Book of Abstracts, 

Geochemistry Division Abstract No. 32.

Lewan, M. D., 1997, Experiments on the role of water in petroleum formation, 

Geochimica et Cosmochimic'a Acta 61, pp. 3692-3723.

Lewan, M. D., Comer, J. B., Hamilton-Smith, T., Hausenmuller, N. R., Guthrie, J. M., 

Hatch, J. R., Gautier, D. L., and Frankie, W. T., (1995), Feasibility study on 

material-balance assessment of petroleum from the New Albany Shale in the Illinois 

Basin: U.S. Geological Survey Bulletin 2137, 3 Ip.

Lewan, M. D., Tannenbaum, E., and Ramini, H., 1997, Petroleum formation in Senonian 

carbonate source rocks of the Dead Sea basin: American Association of Petroleum 

Geologists Annual Meeting, Dallas, TX, April 6-9, 1997, Program and Abstracts, v. 

6, p. A69.

Lillis, P. G., Lewan, M. D., Warden, A., Monk, S. M., and King, J. D., 1999,

Identification and characterization of oil types and their source rocks in The oil and 

Gas Resource Potential of the 1002 Area, Arctic National Wildlife Refuge, AlasSka: 

Chapter OA, U. S. Geological Survey Open-File Report 98-34, p. OA-1 to OA-60.

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American Association of Petroleum Geologists Bulletin 72, p. 399-415.

Noble, R. A., Wu, C. H., and Atkinson, C. D., 1991, Petroleum generation and migration 

from Talang Akar coals and shales offshore N. W. Java, Indonesia: Org. 

Geochem. 17, p. 363-374.

Pepper, A.S. and Corvi, P.J., 1995, Simple kinetic models of petroleum formation.

Part I: oil and gas generation from kerogen Marine and Petroleum Geology 12, 

p. 291-319.

Quigley, T. M. and Mackenzie, A. S., 1988, The temperatures of oil and gas formation in 

the subsurface: Nature 333, p. 549-552.

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River source facies by hydrous pyrolysis Important implications for basin models: 

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Environment, and Human History (eds. J. O. Grimalt and C. Dorronsoro), 

A.I.G.O.A. Publishers, p.188-191.

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theoretical constraints on the generation and composition of natural gas: 

Geochimica et Cosmochimica Acta 62, p. 1599-1617.
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Tissot, B. P. and Welte, D. H., 1984, Petroleum Formation and Occurrence: SpringVerlag, Berlin, 699 p.

10
Table 1: Description of immature source rocks subjected to hydrous pyrolysis.

Kerogen Type

Rock Unit

Sub-Rock Unit

Geologic Age

Sample Number

Location

Basin

TOC (wt. %)

Lithology

Collaborators*

Type-I

Green River Fm.

mahogany shale

Eocene

930923-8

Utah

Uinta

15.23

marlstone

Ruble1 "

Type-II

New Albany Sh.

Clegg Creek Mbr.

Mississippian

931026-3

Indiana

Illinois

14.34

claystone

Guthrie121

Type-US

Ghareb Limestone

"oil shale"

Cretaceous

930616-9

Israel

Dead Sea

14.14

limestone

Tannenbaum

Type-US

Ghareb Limestone

"oil shale"

Cretaceous

930608-6

Jordan

Dead Sea

16.63

limestone

Ramini131

"Collaborator references are [1] Ruble and others (1994); [2] Lewan and others (1995); 

[3] Lewan and others (1997); and [4] Dias and others (1997). 

[5] F. Behar and F. Lorant (in preparation)
Table 2: Hydrous-pyrolysis experimental numbers and 

conditions considered in this study. All experiments were 

conducted for 72 hours.

Experiment (HP-) Number Designation

Temperature

fC)

160.0

180.0

200.0

220.0

240.0

270.0

280.0

285.0

300.0

307.5

310.1

315.0

320.3

322.5

330.0

337.5

340.2

345.0 

350.0

355.1

360.3

365.0

Type-I

930923-8

2186

2187.

2188

2189

2190

2109

NE

2110

2111

2114

NE

2115

NE

2116

2117

2118

NE

2119

2107

2108

.2113

' 2112

Type-II

931026-3

NE

NE

NE

NE

NE

2066

NE

2073

2067

NE

2074.

NE

2068

NE

2075

NE

2076

NE

2070

2078

2071

2085

Type-US

930616-9

NE

NE

2318

NE

2319

NE

2320

NE

2326

NE

2337

NE

2336

NE

2335

NE

2334

' 2321

2317

2316

2327

2314

Type-US

930608-6

NE

NE

2351

NE

2352

NE

2353

NE

2344

NE

2354

NE

2361

NE

2362

NE

2363

2368

2348

2347

2345

2346

Type-UI

WX-3

NE

NE

2399

NE

2400

NE

2667

NE

2635

NE

2396

NE

NE

NE

2637

NE

NE

NE

2398

NE

NE

NE

NE = No experiment was conducted at this temperature for 72 hours.

12
Table 3: Volume of hydrocarbon-gas (Cj-Cf) generated and calculated GOR for source rocks subjected to hyd

experiments for 72 hours. Type ESI denotes Israeli Ghareb Limestone and Type IISj denotes Jordanian Ghare

Experimental

Temperature

CO

160.0

180.0

200.0

220.0

240.0

270.0

280.0

285.0

300.0

307.5

310.1

315.0

320.3

322.5

330.0

337.5

340.2

345.0

350.0

355.1

360.3

365.0

 Type IVolume

(mcf/kg TOC)

2.4

3.5

5.1

6.4

13.8

45.0

81.5

161.7

234.6

. _ 

307.7

454.4

584.8

704.6

1047.3

1340.8

1533.2

1710.9

1898.3

GOR

(ftVbbl)

NO

NO

NO

NO

NO

NO

1240

801

924

922

714

648

687

458

401

463

434

492

........ .--Tvne II 1 Jrc 1L

Volume

(mcf/kg TOC)

112.9

129.9

232.6

339.6

495.5

726.3

967.0

1374.8

1582.9

1850.8

2030.9

GOR

(ftVbbl)

2381

1037

1522

1243

1122

978

992

935

768

944

1006

Tvne II^i jype jj^i

~ Volume

(mcf/kg TOC)

13.3

55.8

205.1

410.8

517.1

795.4

1033.5

1438.6

1581.9

1861.9

2117.7

2409.1

2688.8

GOR

(ftVbbl)

NO

NO

1262

923

754

606

559

509

505

527

606

716

757

Tvne II^i lype Ulij

Volume

(mcf/kg TOC)

5.0

 

21.1

112.5

297.5

422.3

667.0

1004.0

1473.5

1549.8

1865.1

2123.8

2349.6

2942.8

1*

GOR

(ftVbbi)

NO

NO

1513

832

639

503

481

382

389

408

439

522

630
3000

^2500-

O

OhJJ2000

»+i 

o

<g 1500-

0

c 

o

 S 1060

CO

o 

O

500-

0

i i i i ] r i i r i i i r

150

© Mahogany (Type-l)

 New Albany (Type-lI)

A Ghareb-lsrael (Type-llSS)

A Ghareb-Jordan (Type-llSj)

D Wilcox Lignite (Type-Ill)

200 250 .

A 

/ 

>/

300

Mydrous Pyrolysis Temperature (°C for 72 h)

Figure 1: Volume of gas generated from source rocks with different kerogen types subjected to hydrous-py

between 270 and 365°C for 72 hours.
3000

2500-

2000-

_Q 

_Q

^1500

cr: 

O 

O 1000

500-

0

I I O Mahogany (Type

 New Albany (Typ

A Ghareb-lsrael (T

A Ghareb-Jordan (

D Wilcox Lignite (T

250 270 290 310. 330 350

Hydrous Pyrolysis Temperature (°C for 72 h)

Figure 2: Gasroil ratios (GOR) for source rocks with different kerogen types subjected to hydrous-py

between 270 and 365°C for 72 hours.
7000

Hydrous Pyrolysis

© Mahogany (Type-l)

Anhydrous Pyrolysis

(Quigleyand Mackenzie, 1988)

 New Albany (Type-ll)

Ghareb-Israel (Type-IISi) 

A Ghareb-Jordan (Type-l ISj) 

D Wilcox Lignite (Type-Ill)

_Q

,0 4000-

250 270 290 310 330 350 

Pyrolysis Temperature (°C for 72 h) 

Figure 3: Comparison of gasioil ratios (GOli) for source rocks with different kerogen types subjec

anliydrous-pyrolysis temperatures between 270 and 365°C for 72 hours.
4000-

3500-

3000

25*2500-1

O 1500

O

1000-

500-

250

ii i i r i i r

Woodford Shale

 Anhydrous

- ©- Hydrous

0

i i r i i 

. - -Q

I i T \ 1 I I I I I I T

270 290 310 330 350 

Pyrolysis Temperature (°C for 72 h)

Figure 4: Comparison of gasioil ratios (GOR) for aliquots of a sample of Woodford Shale (Type-II) subjec

anhydrous-pyrolysis at 300, 330, and 350°C for 72 hours. Original data reported by Lewan (1997; Tables 2